1. Field of the Invention
The present invention relates to a hard disk drive, and more particularly, to a hard disk drive having an air flow accelerating device to improve a feature of taking-off and landing of a slider where a magnetic head is mounted.
2. Description of the Related Art
A hard disk drive is one of auxiliary memory devices of a computer, to read out data stored in a magnetic disk or record data on the magnetic disk by using a magnetic head.
FIG. 1 is a plan view illustrating a conventional hard disk drive. FIG. 2 is an enlarged perspective view illustrating a landing zone of the disk shown in FIG. 1.
Referring to FIGS. 1 and 2, a conventional hard disk drive includes a magnetic disk 20 that is a recording medium for recording data, a spindle motor 30 installed on a base plate 10 for rotating the disk 20, and an actuator 40 having a magnetic head 41 for recording and reproducing data with respect to the disk 20.
The disk 20 is typically provided as one or a plurality of disks separated a predetermined distance from each other and installed to be rotated by the spindle motor 30. A landing zone 21 where a slider 42 having the magnetic head 41 mounted thereon is accommodated when power is turned off is provided within an inner circumference of the disk 20. A data zone 22 where a magnetic signal is recorded is provided outside the landing zone 21.
The actuator 40 is pivotable around a pivot shaft 47 installed on the base plate 10 by a voice coil motor 48. The actuator 40 includes an arm 46 pivotably coupled around the pivot shaft 47. The magnetic head 41 is integral with the slider 42 and a suspension 44 is installed at the arm 46 for supporting and elastically biasing the slider 42 toward a surface of the disk 20.
In the conventional hard disk drive having a structure as described above, during recording/reproducing of data, lift generated by rotation of the disk 20 and an elastic force provided by the suspension 44 act on the slider 42 having the magnetic head 41. Accordingly, the slider 42 maintains a lifted state above the data zone 22 of the disk 20 at a height where the lift and the elastic force are balanced and the magnetic head 41 records and/or reproduces data to/from the disk 20. When power is turned off and the disk 20 stops rotating, since the lift acting on the slider 42 disappears, the slider 42 should be out of the data zone 22 of the disk 20 in advance of the loss of lift to prevent damage of the data zone 22 as the slider 42 contacts the data zone 22. That is, if the arm 46 of the actuator 40 pivots to be moved above the landing zone 21 before the rotation of the disk 20 completely stops, damage to the data zone 22 when the disk stops rotating completely is preventable.
When the power is turned on and the disk 20 begins to rotate, the lift is generated so that the slider 42 is lifted. The lifted slider 42 is moved to the data zone 22 of the disk 20 as the arm 46 pivots so that the magnetic head 41 performs recording and/or reproduction of data on/from the data zone 22 of the disk 20. To facilitate lift of the slider 42 by reducing a contact area between the slider 42 and the landing zone 21 of the disk 20, a plurality of bumps 21a, each having a crater shape, may be formed on the landing zone 21 by a laser, as shown in FIG. 2.
FIGS. 3A through 3C show a sequence of lifting the slider 42 having the magnetic head 41 mounted thereon by the rotation of the disk.
Referring to FIG. 3A, the slider 42 rests on the bumps 21a formed on the surface of the disk 20 before the disk 20 rotates. When the power is supplied to the hard disk drive and the disk 20 is rotated, the slider 42 is gradually lifted by receiving the lift generated by the rotation of the disk 20 so that the contact area with the bumps 21a decreases, as shown in FIG. 3B. Since a side of the slider 42 to which air is supplied by the rotation of the disk 20 is lifted first, the slider 42 is initially slightly inclined at a small angle. When the rotation speed of the disk 20 reaches a regular rotation speed after a few seconds, the slider 42 is completely lifted to maintain a predetermined distance from the surface of the disk 20, as shown in FIG. 3C. In the completely lifted state, the slider 42 is moved to the data zone 22 of the disk 20 as the arm 46 shown in FIG. 1 pivots. However, when the power of the hard disk drive is turned off, the rotation of the disk 20 is stopped and the slider 42 will be urged toward the disk 20 by an elastic force B of the suspension 44.
In a contact start stop type magnetic head loading/unloading system, when the disk 20 rotates again after being stopped, the slider 42 is abraded by the surface of the rotating disk 20 until the slider 42 is completed lifted by the lift generated by the rotation of the disk 20.
The abrading problem also occurs when the disk 20 stops rotating and the slider 42 is accommodated in the landing zone 21 of the disk 20. That is, as the rotation speed of the disk 20 is gradually reduced, the lift lifting the slider 42 decreases. Thus, the slider 42 is lowered and contacts the surface of the disk 20. The slider 42 is abraded by the surface of the disk 20 for a long time so that the magnetic head 41 mounted on the slider 42 may be damaged, thus deteriorating reliability of the hard disk drive. Also, particles are generated due to the abrasion. If a lift height of the slider 42 is gradually reduced, a distance between the bumps 21a and the slider 42 gradually decreases and the above problems become more serious.